


The Challenge

by snassty



Category: Undertale (Video Game)
Genre: Anal Fingering, Anal Sex, Dirty Talk, F/M, Horndog Sans, M/M, Other, Plot What Plot/Porn Without Plot, Reader-Insert, Skeleton Ghost Penis, aggressive sex, cum inflation maybe?, dick expansion?? idk it's not super weird it's like normal size stuff, reader is assumed to be of legal and consenting age, reader's sex/gender are undefined
Language: English
Status: Completed
Published: 2017-04-21
Updated: 2017-04-21
Packaged: 2018-10-22 00:57:51
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 1,302
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10686489
Author URL: https://archiveofourown.org/users/snassty/pseuds/snassty
Summary: You and Sans are watching TV late at night. Gee, I wonder what will happen.(The result of challenging myself to write a smut fic with a completely ambiguous reader.)





	The Challenge

You like Sans.

The television is playing some horrible Syfy movie that you're only half paying attention to, curled up on the couch next to your skeleton friend.

You like Sans a lot, if the thumping in your chest is any indication.

He's much more bold over text than he is in person. You've read and re-read the raunchy sexts he's sent you in the middle of the night, kept them for getting yourself worked up when you're alone. Every time you meet, though, he's always kind of shy and awkward.

Right now he has his eyes trained on the screen, his hands stuffed in the front pocket of his hoodie, where you can see them fidgeting slightly. It's endearing. You throb between your thighs and curl your hands into fists at your sides.

"H-hey." Your mouth feels dry, and the word barely chokes past your lips. You clear your throat and try again. "Hey, uh."

"S'up?" He turns that ever-present grin on you.

You spit your question out before you can change your mind. "Wanna fuck?" Your voice comes out slightly huskier than intended.

His eyelights shrink to practically nonexistent, and his smile falters a tiny bit, and for a moment, you panic. But then, with speed you'd never thought him capable of, he's got a fistful of the front of your shirt, yanking you into his personal space.

"Thought you'd never ask," he purrs – and then suddenly he's kissing you like he's starving for it, and you vaguely realize that he has something akin to lips, but analytical thought really isn't your strong point right now. The teeth you've only ever seen bared in a smug grin scrape against your own in Sans' eagerness to taste you.

You remember, after a few moments, that you have to breathe.

Sans chuckles lowly as you break away gasping for air. He licks his teeth, making a lewd slurping sound, and puts his hands on your hips, pulling you into his lap. With a soft growl, he lunges for your mouth again.

"I'm a bit of a hands-on learner," he says, his words clear as ever despite your mouths dancing a tango, "so, uh... Let me know if I get a little too handsy, yeah?" You moan an eager "mmhmm" into his mouth, and his skeletal hands venture down your back and into your pants.

He pulls away from the kiss, and you suck on his tongue as it retreats. "Nice ass you got there, kiddo," he murmurs, licking and nibbling at your neck. "Y'know what'd make it even better?" He gives you a squeeze and bites your earlobe. "If my cock was in it," he growls. You whine and rock your hips, and he chuckles. "Yeah? Is that what you want?"

"Uh huh," you nod, your hands fumbling with your zipper.

"That's right, cutie, take those pants off for me." His voice is lower and growlier than usual, and it works you up in all the right ways. You hurriedly shimmy out of your jeans and leave them on the floor in favor of crawling back into Sans' lap – and when you do, you find yourself sitting on a bulge in his shorts.

He must sense your surprise, because he gives you a cocky grin and says, "What? Did you think I'd offer to fuck you without actually having the means to do so?" He doesn't give you a chance to answer, instead sliding a finger down between your cheeks to tease your asshole. You arch your back and swallow a sound of enjoyment. He notices. "Yeah, you like that, huh..." He rubs and circles the hole with the tip of his finger.

"Saaaans," you whine. He lets out a noise somewhere between a purr and a growl.

"Fuck, you sound so good moaning my name like that..." He tugs his shorts down just enough to let free his erection: bright blue, moderate length, and... honestly much less girthy than you'd expected. "Come on, kid," he snorts. "I wanna fuck you, not split you in half."

Fair enough. You still want it inside you. It glistens; you run your fingers up and down its length, marveling at the way it feels like it's already lubricated.

"You like it?" he murmurs. You shiver, nodding. "Good. Cause it's goin' in you right..." He grips you by the hips and moves you forward, rubbing his length between your cheeks. "About..." He lifts you up slightly, and you feel the head of his cock press against your asshole. "... now." He eases you down, and it's really not unpleasant considering his size. It hurts just enough.

"Feel good, kiddo?" Sans purrs, his thumbs rubbing circles on your thighs. You nod. His smile turns into a mischievous smirk. "Mm, then why don't we up the ante a little?" You're confused, but only for a moment – only until you feel him starting to grow thicker inside of you. You let out a shout, your body jolting, and his eyelights dilate hazily. "Mmn, that was a nice little squeeze..."

Embarrassed, you press you face into his neck. He slides his hands up the back of your shirt and traces patterns on your back, kissing your throat. You're vaguely aware of bad acting coming from the TV behind you, but slowly, your arousal comes back as the pain fades. You grunt and straighten your back, sitting up with your hands braced on Sans' shoulders.

"You ready?" He caresses your thighs on his way to getting a good hold on your hips. You nod. He guides you as you lift yourself up, and you bite your lips and barely contain a moan – you can feel him tugging at the sensitive skin of your hole as he pulls out. He holds you in place, then lowers you back down, craning his head back blissfully. "Fuck, kid," he groans, fingers digging into your hips. The stretch is sublime, and you feel so deliciously full. You want more. So you do it again, lifting yourself off him and thrusting back down.

"That's it, kitten," he moans, opening his sockets to gaze at you hungrily. "Ride me with that tight, hot little ass of yours..." He slips a hand under his shirt and lazily fingers his lowest ribs as he watches you, and that only works you up more. You curl your fingers over yourself between the two of you, and he purrs – the way he grins flashes his fangs. "That's fucking hot," he growls. "Watching you touch yourself while you ride my cock..." He's started to buck up to meet your downward thrusts. "You're gonna cum for me, right, baby?" You nod eagerly, working yourself feverishly. "Yeah? You want me to cum for you too?" He licks his teeth as you manage to spit out the word "inside." "You want me to fill you up?" He grabs your hips with both hands, slamming up into you with a feral passion. "You're gonna fuckin' take it..." His voice is deep and gravelly now, punctuated by animalistic grunts. "Fuckin' take it all," he latches onto your neck, knocking you down to the floor. You cry out in ecstasy as he fucks you to orgasm, your release splashing out onto his bones – but he keeps rutting into you, growling, until he finally roars, "take it, fucking take my cum, take it all...!" He thrusts into you and arches his spine, and you feel him release inside you, hot and thick, and he keeps thrusting, and he keeps cumming, staring down at you with his fangs bared, his skull illuminated by the flickering screen of the television...

You'd be lying to yourself if you said the sight wasn't just a little bit frightening. But you'd be lying even more if you said it didn't turn you the fuck on.


End file.
